Method and apparatus for continuously sizing, preforming or casting

ABSTRACT

A method and an apparatus for continuously sizing, preforming or forming metal objects include a plurality of molds arranged in a substantially vertical column and which collectively define a mold cavity. Each mold is separable into at least two mold sections. A retaining mechanism retains the molds in the vertical column. A mechanism separates the bottom mold into sections and removes the mold sections and positions the sections on a top mold of the column to form a new top mold. Preferably, the mechanism includes first and second arms which are rotatable between the bottom and the top mold positions and which grasp and move the mold sections from the bottom of the column to the top of the column.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to continuous metal casting. Inparticular, it relates to the continuous casting of metal using aplurality of molds arranged vertically in a column, each mold separableinto sections, such that the bottom mold is removed and placed on top ofthe column to form a continuous casting column.

2. Description of the Prior Art

Metal casting has been traditionally done using molds having individualand separated cavities for each part or item that is being molded. Thismolding procedure constitutes a "batch" type of process wherein the moldis reused. A batch process is inefficient in both the usage of labor andcapital equipment since the mold is oftentimes being used to cool metalalready solidified to a temperature in which it can be handled.

There have been several attempts in trying to develop continuous metalcasting processes. The Waring U.S. Pat. No. 3,771,586 describes acontinuous casting apparatus that includes a plurality of mold halvesattached to two continuous vertical belts which bring the mold halvestogether to form a continuous casting column and which then separate themolds at a lower position, revealing the solidified metal. Although theWaring Patent describes a continuous caster, the continuous caster ofthe Waring Patent has half the molds not being used to cast metal at anyone time. Since the molds are expensive, unnecessary capital is beingused.

The Hallsworth U.S. Pat. No. 2,843,895 describes a wheel-type casterhaving individual molds disposed on the wheel and which are presented ina sequence to a pouring location, a molding box unloading station and amolding box loading station. Although the apparatus of the HallsworthPatent may produce castings in a continuous manner, the molding processitself is still a batch process since each individual mold producesindividual separate castings.

The Nakagawa U.S. Pat. No. 2,184,257 is similar in concept to theHallsworth Patent in that it shows a centrifugal hollow ball castingmachine in which individual molds are carried on an endless chain belt.The molds are charged with molten metal and rotated by an endless beltso that the molten metal inside the cavity is slung and distributedclosely onto the cavity surfaces to form a hollow ball. However, eachmold produces a distinct casting and in itself is a batch mold.

Further attempts in trying to develop a continuous casting process aredescribed in the Green U.S. Pat. No. 1,863,371 and the Brinton U.S. Pat.No. 2,486,388. The Greene Patent shows a vertically disposed wheelhaving a plurality of molds disposed adjacently along the periphery ofthe wheel. Each of the molds is separated into two hinged halves. At amolten metal pouring position, the halves are brought together due tothe rotation of the wheel and then opened when the metal has solidifieddropping out the casting. The molten metal is continuously poured andthe balls continuously drop out of molds that are being opened. However,such an arrangement is quite expensive since a large number of molds areneeded and the wheel to rotate the molds must be structurally strongenough to handle the number of molds needed.

The Brinton Patent describes an apparatus that has a plurality of moldsdisposed on an inclined frame with two channels. The molds in the firstchannel proceed downwardly along an incline past a molten metal pouringstation in which molten metal is poured along a slot in the mold andflows into the mold cavity. Each mold section defines a mold cavity withan adjacent mold section. When the metal has hardened at the bottom ofthe incline, the bottom-most mold section is broken away and pushed to asecond channel on the incline, dropping the casting. The second channelon the incline includes a row of mold sections that are progressivelypushed upwardly to resupply the first channel with usable molds. Again,this type of continuous metal casting process needs an excessive numberof expensive molds.

In a plastic molding process, described in the Hegler et al U.S. Pat.No. 4,212,618, a plurality of molds are disposed in a horizontal rowwith the front end of the row being connected to an extruder from whichmolten plastic is supplied. A solidified plastic pipe exits the back endof the row. A plurality of rollers move the row of molds away from theextruder and a pair of arms grasp the mold halves at the end of themolding run and return the molds back toward the front end near theextruder. Although this is a continuous process, it is a plasticextrusion process unsuitable for processing of molten metal.

SUMMARY OF THE INVENTION

The present invention includes a method and an apparatus forcontinuously casting metal objects using a plurality of molds arrangedin a substantially vertical column and which collectively define asubstantially vertical mold cavity. Each mold includes at least two moldsections separable from each other. A retaining mechanism retains fthemolds in the vertical column. A mold positioning mechanism separates themold sections of the bottom mold and removes the bottom mold sectionsand positions the sections on the top mold forming a new top mold.Preferably, the mechanism includes first and second arms, each armrotatable between the bottom and the top mold positions for grasping andmoving the mold sections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of the apparatus of the pesent inventionbeing used in a process for forming milling balls.

FIG. 2 is an elevational view of the apparatus of the present invention.

FIGS. 4-6 are elevational views of the apparatus of the presentinvention with portions being shown in cross section illustrating theoperation of the apparatus of the present invention.

FIG. 3 is a cross sectional view taken along the line 3--3 in FIG. 2.

FIG. 7 is an enlarged fragmentary view of the pusher mechanism.

FIG. 8 is a cross sectional view taken along the line 8--8 in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus of the present invention is generally indicated at 10 inFIG. 1 and is illustrated as part of an apparatus 12 for forming millingballs 16. The apparatus 12 includes a well known induction furnace 14for melting metal and supplying molten metal to the apparatus 10 of thepresent invention. The apparatus 10 forms grinding balls 16. Grindingballs are shown for illustrative purposes and the apparatus 10 is usedto form other objects. The grinding balls are then processed through arotating tube 18 and through a chute 20 into a compression device 22.The tube 18 and the compression device 22 are described in U.S. Pat. No.4,003,232 which issued to the same applicant as the applicant of thepresent application and is incorporated herein by reference.

It should be understood that although a specific example of the use ofthe apparatus 10 is given above, the apparatus 10 of the presentinvention is also usable in other processes, such as a forging process.The present invention has versatility in being used to cast metalobjects of various shapes, especially in high volume situations, and isnot limited to the specific example of FIG. 1. In particular, theapparatus 10 is useful in a high volume forging process for preformingsuch items as axe heads or hammer heads wherein the preformed hammerhead is transferred to the forge in a solid but hot condition therebyconserving energy that is normally wasted in reheating cast objectswhich are subsequently forged. In addition, the present invention isuseful in sizing operations.

As illustrated in FIG. 2, the present invention 10 is normally mountedon a frame structure 24. The particular configuration of the framestructure 24 is not particularly important to the present invention, butshould be of sufficient strength to hold the apparatus 10 due to theweight of the molding blocks being used and the metal castings beingproduced. The frame structure 24 includes a bottom set of four legs 26that are mounted on a floor 28. The legs 26 are joined at the top by aplate 30 having an aperture 32 located in a substantially centralposition of the plate 30. The floor 28 also has an aperture 34 insubstantial vertical alignment with the aperture 32.

Four substantially vertical support members 36a, 36b, 36c and 36d areattached to the plate 30. Each support member is attached to the plateproximate a corner of the plate 30 and extends upwardly. A mold supportplate 37 is fixedly attached to each of the members 36a, 36b, 36c and36d. The plate 37 has a centrally located aperture 50 that is alignedcoaxially with the apertures 32 and 34.

A plurality of molds 38, 40, 42, 44 and 46 are separated into twohalves. The molds are arranged in a substantially vertical column 45stacked one on top of the other. The molds are separable into halves anddefine a continuous substantially vertical casting cavity 92, as will bediscussed subsequently.

The column 45 is disposed between the members 36a, 36b, 36c and 36d andis frictionally retained in a vertical position such that when thebottom mold 38 is removed, the remaining portion of the column does notdrop down.

More specifically, the column 45 is frictionally held against retainingbars 52, 53, 56 and 60 by screw-type clamps 64, 66, 68 and 70, as bestillustrated in FIG. 3. The retaining bars 52, 53, 56 and 60 and thescrew-type clamps 64, 66, 68 and 70 extend along the members 36a, 36band 36c and 36d to frictionally engage only molds 40, 42 and 44 so thatthe bottom mold 38 may be pulled out from the column and inserted on topof the column 45 as will be discussed subsequently.

The screw-type clamps 64 and 66 provide a force in the general directionof arrow 72 to frictionally hold molds 40, 42 and 44 against edges ofthe bars 53 and 56. The screw-type clamps 68 and 70 provide a force inthe general direction of arrow 74 to frictionally hold molds 40, 42 and44 against the bars 52 and 60.

The retaining bar 52 and the retaining bar 53 are welded along an innerfacing corner 54, along oppositely disposed surfaces thereof, forming acorner 55 for retaining a corresponding corner of molds 40, 42 and 44.The retaining bar 56 is welded to member 36b along an edge surface 58.Similarly, the retaining bar 60 is welded to the member 36d along anedge surface 62.

Since the screw-type clamps 64, 66, 68 and 70 are of similarconstruction, only the clamp 64 will be described in detail with theunderstanding that clamps 66, 68 and 70 have like elements. The clamp 64includes a housing 76, a friction bar 78 and a clamping bolt 80. Thehousing 76 is welded along a surface 82 to a surface 84 of the member36d to retain the clamp 64 in a fixed position and to provide supportfor the clamping force. The clamping bolt 80 threadably engages a nut 83welded to the housing 64 and, when turned, forces the friction block 78against the molds 40, 42 and 44 to clamp the molds against the retainingbar 53. The screw-type clamp 66 is welded to the member 36c along asurface 86 and provides a force to frictionally clamp molds 40, 42 and44 against the retaining bar 56. Similarly, the screw-type clamp 68 iswelded to a surface 88 of member 36c and the screw-type clamp 70 iswelded to a surface 90 of member 36b to provide a force to clamp themolds 40, 42 and 44 against retaining bars 60 and 52, respectively.

As previously discussed, each of the molds 38, 40, 42, 44 and 46 isseparable into at least two mold sections. The mold sections of each ofthe molds will be referred to by the letter character a for moldsections illustrated on the left-hand side of the column, for example,mold section 38a, and the letter character b for mold sectionsillustrated on the right-hand side of the column, for example, moldsection 38b. As illustrated in FIG. 4 and previously described, themolds 38, 40, 42, 44 and 46, when positioned on top of each other in thevertical column 45, define the molding cavity 92 which extendsthroughout the length of the column 45. The molding cavity 92 is a truecontinuous molding cavity wherein molten metal is poured continuously,moves downwardly and solidifies continuously.

Referring back to FIG. 2, the molds are moved from the bottom of thecolumn 45 to a top position on the column to provide the continuousmolding cavity. Each of the mold sections has fixedly attached theretoand extending outwardly therefrom a mold handle. The mold handle isdesignated by 94 for each of the mold handles of the mold sections ofthe left side of the column, and designated by 96 for the mold handlesof the mold sections on the right side of the column. The mold handles94 are grasped by an arm mechanism 98 and the mold handles 96 aregrasped by an arm mechanism 100.

The arm mechanism 98 includes an upper gripping jaw 102 and a lowergripping jaw 104. The gripping jaws are fixedly attached to alongitudinal connecting arm 106 that is rotatable about an axis 108. Thearm 106 is fixedly attached to a rotatable connecting arm 107. The armmechanism 98 is rotatably secured to a platform 110 by a plurality ofbearing blocks 112, 114 and 115 which permit the rotation of the arm 106and the gripping jaws 102 and 104. A stepper motor (not shown) providesthe motive force for rotating the arm 106 and the gripping jaws 102 and104.

The arm 106 and the gripping jaws 102 and 104 are also moved in adirection generally perpendicular to the column 45 as indicated byarrows 118 by a hydraulic cylinder 120 having a piston rod 122. Thepiston rod 122 is connected to the arm 106 and the gripping jaws 102 and104 to move the jaws 102 and 104 toward and away from the column 45.

Similarly, the arm mechanism 100 includes gripping jaws 124 and 126attached to a longitudinal connecting arm 128 that is rotatable about anaxis 142. The arm 128 is fixedly attached to a rotatable connecting arm130. The arm mechanism 10 is rotatably secured to a platform 132 bybearing blocks 134, 136 and 146. The connecting arm 130 is attached to apiston rod 138 of a hydraulic cylinder 140. Similar to arm mechanism 98,the arm mechanism 100 uses the hydraulic cylinder 140 to push the jaws124 and 126 toward and away from the column 45 in the direction ofarrows 144 and uses a stepper motor (not shown) to rotate the arm 128and the jaws 124, 126 about the axis 142.

The jaws 102, 104, 124 and 126 are of similar construction and only thejaw 102 will be described in detail, with the understanding that thejaws 104, 124 and 126 have like elements. Referring to FIG. 4, the jaw102 contains upper jaw clamping member 148 and lower jaw clamping member150. The members 148 and 150 are pivotally attached to a connecting bar152 at an upper pivot point 154 and a lower pivot point 156,respectively. The bar 152 is connected to the arm 106 by a transducerbox 158. The jaw 102 is pneumatically operated. A pneumatic fluid, suchas air, is supplied to the transducer box 158 by tubing 160 and 162under pressure from a source (not shown) which selectively delivers airto the box 158 such that the jaw members 148 and 150 are forced apartand pushed together to grasp and release the mold handles.

Each of the mold handles 94 and 96 include notches 164 and 166,respectively, as best illustrated in FIG. 3. Referring back to FIG. 4,the upper jaw member 148 includes a notch-engaging protrusion 168 andthe lower jaw member 150 includes a notch-engaging protrusion 170. Theprotrusions 168 and 170 extend from the respective jaw members towardeach other. When the jaw 102 is in a closed position, the protrusions168 and 170 engage the notch 164 so that the jaw securely holds the moldsection, as illustrated by the lower jaw 104. The protrusions 168 and170 disengage from the notch when the jaw members 148 and 150 are spreadapart from each other and the jaw 102 is placed in an open position.

A pusher mechanism 182 is illustrated in FIGS. 7 and 8. The pushermechanism includes a hydraulic cylinder 184 pivotally mounted on a base186 that is fixedly attached to the frame structure 24. The hydrauliccylinder 184 is pivotally mounted using a pin 188. The pusher mechanism184 further includes a pusher member 190 that is fixedly attached to apiston rod 192 of the hydraulic cylinder 184. The pusher member 190extends over the column 45 for engaging the top mold 46.

FIGS. 4-6 illustrate an operational cycle of the present invention. Asstated previously, the molds 38, 40, 42, 44 and 46, when stacked, formthe column 45 and a continuous mold cavity 92. Molten metal is suppliedfrom a dish 172 to a funnel 174. Metal from the dish is poured into thefunnel 174 manually or automatically. The manner of pouring the metalinto the funnel is not particularly important to the present invention.The funnel 174 preferably rests on a platform 176 that is disposed abovethe column 45 and contains an opening 178 through which a nozzle 180 ofthe funnel extends into the mold cavity 92. The funnel 180 extendssufficiently into the cavity 92 to deliver molten metal such that airentrainment in the molten metal is minimized. In addition, the diameterof the funnel is smaller than the diameter of the mold cavity where themolds in the column meet adjacent molds so that air is permitted toescape up the column and out between the molds as the metal goes to thebottom of the mold.

It is believed that as the molten metal fills the cavity, the moltenmetal moves in a spiral movement eliminating any parting line andreduces interior shrinkage.

As the portion of the cavity 92 formed by mold 44 and lower portions ofthe cavity formed by mold 46 are filled with molten metal, the hydrauliccylinders 120 and 140 are actuated, moving the arm mechanisms 98 and 100toward the column 45. Simultaneously, the pneumatic system is activated,opening the lowering gripping jaws 104 and 126 so that the jaws are openwhen approaching the mold handles 94 and 96 of the respective moldhalves 38a and 38b. At the start of each cycle, the upper jaws 102 and124 are also in an open position so that the handles 94 and 96 of thetwo mold sections 46a and 46b, respectively, do not block the movementof the lower gripping jaws. When the lower gripping jaws 104 and 126 arein position, the jaws are placed in a closed position with theprotrusions of each of the jaw members engaging the notches of therespective mold handles. The hydraulic cylinders 120 and 140 areactuated to move the arm mechanisms 98 and 100 away from the column,removing the mold sections 38a and 38b. The column 45 is held verticallyin place by screw-type clamps 64, 66, 68 and 70. The lowermost portionof the cavity 92 is exposed, revealing the metal in a solidifiedl castform ready for further processing.

Referring to FIG. 5, the arm mechanisms 98 and 100 are rotated about theaxes 108 and 142, respectively, placing them in an upper position asillustrated in FIG. 4. The mold sections 38a and 38b are now in positionto be placed as the top-most mold sections on the column 45.Simultaneously with the rotation of the arm mechanisms 98 and 100, thepusher mechanism 182 has pushed down the column 45 to make room for theholds 38a and 38b.

The hydraulic cylinders 120 and 140 are then actuated to once again movethe arm mechanisms 98 and 100 toward the column 45 to insert the moldhalves 38a and 38b at the top of the column, as illustrated in FIG. 6.The mold halves 38a and 38b, when placed together at the top of thecolumn, form the top portion of the mold cavity 92. While the moldhalves 38a and 38b are being placed at the top of the column, metal isbeing continuously poured into the mold cavity filling the portion ofthe cavity formed by mold halves 46a and 46b. In addition, the uppergripping jaws 102 and 124, which have been rotated to a lower position,are actuated to open their respective jaw members to a position forengaging the mold handles 94 and 96 of the mold halves 40a and 40b,respectively. At approximately the same moment that the jaw members ofthe gripping jaws 102 and 126 release the mold handles 94 and 96 of themold sections 38a and 38b, the jaws 102 and 124 grip the mold handles 94and 96 of the mold sections 40a and 40b, respectively. The hydrauliccylinders 120 and 140 are then actuated, moving the arm mechanisms 98and 100 away from the column 45 leaving the mold sections 38a and 38b inplace at the top of the column and removing the mold sections 40a and40b from the bottom of the column. The cycle is then repeated byrotating the arm mechanisms 98 and 100.

The present invention has usefullness in a preforming operation bysimply increasing the speed at which the molds are moved from the bottomto the top. Long lengths of hot ribbon of various shapes can be made.The length of ribbon are formed at different speeds depending on thedesired degree of solidification and the type of heat treatment neededfor the subsequent forging, rolling or other finishing step.

In addition, the column of molds can be moved at an even greater speedto be used as a sizing operation in connection with apparatus describedin the Trendov U.S. Pat. No. 4,003,232 wherein hot metal in asemi-liquid state are dropped in the rotating tube for further formingand solidification.

In summary, the apparatus of the present invention provides a mechanismfor continuously casting metal using a minimum number of molds. Metal iscontinuously poured into the top of a column and the solidified castingsare removed at the bottom with only one mold being idle at any one time.

A further important feature of the present invention is that theapparatus is changed over from forming one type of object to forming adifferently shaped object without any down time. When the bottom mold ispulled out of the column, the mold halves for forming a differentlyshaped object are placed on top of the column. Each bottom is replacedwith a top mold for forming the differently shaped object until thecolumn contains only the molds of the differently shaped object. Theresult is no down time with virtually no scrap in changing over.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. An apparatus for continuously casting metal objects, the apparatus comprising:a plurality of molds arranged in a substantially vertical column defining a mold cavity, each mold having at least two mold sections separable from each other and the column having a top mold and a bottom mold; means for retaining the molds in the substantially vertical column; and arms means for separating mold sections of the bottom mold and for removing the bottom mold sections and for positioning the bottom mold sections on the top mold of the column forming a new top mold wherein the arm means includes first and second arm mechanisms disposed on opposite sides of the column and each arm mechanism having first and second gripping jaws, means for rotating the gripping jaws, and means for positioning the gripping jaws towards and away from the column such that when the first gripping jaw is in a lowermost position, the first gripping jaw is movable towards the column to engage and pull out the bottom mold section, and the means for rotating rotates the first gripping jaw to an uppermost position and the second gripping jaw to a lowermost position, and the means for positioning positions the first gripping jaw such that the bottom-most mold section is positionable at the top of the column.
 2. The apparatus of claim 1 wherein the means for positioning the gripping jaws toward and away from the column includes hydraulic cylinder means.
 3. The apparatus of claim 1 wherein the means for retaining the molds in a substantially vertical column includes clamping means for frictionally engaging at least some of the molds between the top and the bottom molds of the column.
 4. The apparatus of claim 3 wherein the means for retaining further includes first, second, third and fourth support posts spaced from each other and arranged to hold the molds in the column and wherein the clamping means includes first and second clamps attached to first and second posts for clamping the molds between the top and the bottom mold against the third and fourth posts and third and fourth clamps attached to the second and third posts for clamping the molds between the top and the bottom mold against the first and fourth posts.
 5. The apparatus of claim 1 and further including means for engaging the top of the column to push the column down after the bottom-most mold sections are placed on top of the column.
 6. The apparatus of claim 5 wherein the means for pushing includes a hydraulic cylinder means and a top mold-engaging member attached to the hydraulic cylinder means such that when the hydraulic cylinder is actuated, the mold-engaging member pushes down on the top mold and then returns to a position permitting another mold to be placed on top of the column.
 7. A process for continuously casting metal objects comprising:a. arranging a plurality of molds in a substantially vertical column to define a continuous mold cavity, each mold having at least two mold sections separable from each other; b. frictionally retaining the molds positioned above the bottom mold in a selected vertical position; c. pouring metal into the mold cavity at the top of the column; d. providing an arm mechanism on both sides of the column with first and second means for gripping and separating the sections of the bottom-most mold from each other and positioning the sections at the top of the column to form a new top mold by rotation of the means for gripping; e. providing a force at the top of the column to overcome the frictional retaining force to move the column downwardly; f. repeating steps c, d and e to provide a continuous metal casting column.
 8. An apparatus for continuously casting metal objects, the apparatus comprising:a plurality of molds arranged in a substantially vertical column defining a mold cavity, each mold having at least two mold sections separable from each other and the column having a top mold and a bottom mold; means for retaining the molds in the substantially vertical column including clamping means for frictionally engaging at least some of the molds between the top and the bottom molds of the column and first, second, third and fourth support posts spaced from each other and arranged to hold the molds in the column and wherein the clamping means includes first and second clamps attached to first and second posts for clamping the molds between the top and the bottom mold against the third and fourth posts and third and fourth clamps attached to the second and third posts for clamping the molds between the top and the bottom mold against the first and fourth posts; and arms means for separating mold sections of the bottom mold and for removing the bottom mold sections and for positioning the bottom mold sections on the top mold of the column forming a new top mold.
 9. The apparatus of claim 8 and further including means for engaging the top of the column to push the column down after the bottom-most mold sections are placed on top of the column.
 10. The apparatus of claim 9 wherein the means for pushing includes a hydraulic cylinder means and a top mold-engaging member attached to the hydraulic cylinder means such that when the hydraulic cylinder is actuated, the mold-engaging member pushes down on the top mold and then returns to a positon permitting another mold to be placed on top of the column.
 11. An apparatus for continuously casting metal objects, the apparatus comprising:a plurality of molds arranged in a substantially vertical column defining a mold cavity, each mold having at least two mold sections separable from each other and the column having a top mold and a bottom mold; means for retaining the molds in the substantially vertical column; arms means for separating mold sections of the bottom mold and for removing the bottom mold sections and for positioning the bottom mold sections on the top mold of the column forming a new top mold; and means for engaging the top of the column to push the column down after the bottom-most mold sections are placed on top of the column including a hydraulic cylinder means and a top mold-engaging member attached to the hydraulic cylinder means such that when the hydraulic cylinder is actuated, the mold-engaging member pushes down on the top mold and then returns to a position permitting another mold to be placed on top of the column.
 12. A process for continuously casting metal objects comprising:a. arranging a plurality of molds in a substantially vertical column to define a continuous mold cavity, each mold having at least two mold sections separable from each other; b. providing clamping mechanisms on a plurality of support posts for frictionally retaining the molds positioned above the bottom mold in a selected vertical position; c. pouring metal into the mold cavity at the top of the column; d. separating the sections of the bottom-most mold from each other and positioning the sections at the top of the column to form a new top mold; e. providing a force at the top of the column to overcome the frictional retaining force to move the column downwardly; f. repeating steps c, d and e to provide a continuous metal casting column.
 13. A process for continuously casting metal objects comprising:a. arranging a plurality of molds in a substantially vertical column to define a continuous mold cavity, each mold having at least two mold sections separable from each other; b. frictionally retaining the molds positioned above the bottom mold in a selected vertical position; c. pouring metal into the mold cavity at the top of the column; d. separating the sections of the bottom-most mold from each other and positioning the sections at the top of the column to form a new top mold; e. providing a hydraulic cylinder to push down at the top of the column to overcome the frictional retaining force to move the column downwardly; f. repeating steps c, d and e to provide a continuous metal casting column. 